Car "detunes" when it wants

[ITHURTZ]

It like the car flips its own switch. Now there is no jerk stutter, or anything but the car can go like it should with the mods I have, then in a blink of the eye the exhaust sounds like a 2.0 straight piped and my performance goes down. I can drive it 100% how it should, wot cruise and it will be fine, then it goes to being a rice burner. Iv gone atleast 1 week of it being nothing but a ricer burner, then it just automatically goes to normal. It can be in its "rice burner" mode for 10min then goes back to normal etc. I dont really know how to explain it, and cant really trouble shoot it because it doesnt STAY performance wise. It is constantly switching between its imaginary "detune" with no hint, buck, tick, tink, smell etc. The only way I know it "detuned" itself is from the exhaust tone. When normal its deep, which it swtiches its slower and the exhaust is a straight piped 2.0, embarrasing to say the least. Any hints or clues?

 

[wanna3]

Its called adaptive learning, pretty much the car watches how you drive and in turn makes the changes it see fit ex. if your more harder on the car it will do things like set vvt activation sooner, make the shifts firmer and later if you have an auto but if you switch between semi agressive and slow and steady then the ecu just changes it parmeters while your driving in that manner, but if you try to hammer it it takes it a few for it to switch to "performance" mode, it might not even do it the 1st time maybe on the 2nd or 3rd time, nothing you can do to get around that w/o a tuner.

 

[ITHURTZ]

It never did this for years. It only started happening once I threw my exhaust on.

 

[sunrun176]

So, when the exhaust sounds louder, does it still seem to be coming from the rear, or does it seem like it's coming from farther forward? If forward, it might be that there's something loose or a hole in the exhaust manifold that (for now) only happens once the system heats up.

A similar thing happened on my old '95 Proteg. Once the exhaust system was heated it expanded the joint between the manifold and the pipe before the cat which made it sound like a straight pipe and the performance (such as it was) dipped significantly, almost to the point that it would stall at idle (due to the lack of back-pressure). Had to have the pipe replaced for ~$350 (mostly labor) IIRC.

Bottom line, gotta get it up on a lift and closely inspect and wiggle the exhaust system to check for gaps, cracks and holes.